Water Intake Calculator

How much water do you need?

Water needs vary with body size, activity, climate and health. A common rule of thumb is about 35 ml per kilogram of body weight per day, which is roughly 2.3 litres for a 65 kg adult. This calculator starts there, then adds about 500 ml for every 30 minutes of exercise and 500 ml for hot or humid weather, since you lose more through sweat.

Hot Indian summers

In peak summer, when temperatures cross 40°C in much of India, dehydration and heat stroke are real risks, especially for outdoor workers, travellers, children and the elderly. Drink water regularly rather than waiting for thirst, and include fluids with salts, like buttermilk, lemon water with a pinch of salt, or ORS, when sweating heavily.

All fluids count

Water from food (fruits like watermelon and cucumber, dal, curd) and other drinks (milk, tea, buttermilk, coconut water) contributes to your intake. Sugary drinks add calories, so plain water is the best everyday choice.

Signs you’re drinking enough

• Pale yellow urine is a simple, reliable check.
• Rarely feeling thirsty, and no headaches or dizziness from dehydration.

Who should be careful

People with kidney disease, heart failure, liver problems or those on certain medicines may need to limit fluids. Pregnant and breastfeeding women need more. Follow your doctor’s advice if you have a medical condition. This is general information, not medical advice.

Related

Check your weight status with the BMI calculator.

Examples

• 60 kg, no exercise, mild weather: about 2.1 litres.
• 60 kg, 30 minutes of exercise, hot summer: about 3.1 litres.
• 80 kg, 60 minutes of exercise, hot summer: about 4.3 litres.

Spread these through the day, with extra during and after exercise.

Tip: keep a bottle at your desk and refill it a set number of times.